trade in iPhones

hi,

i have 5/6 iPhones at home..im living in israel and i wanted to trade all the iPhones and buy the 12 max pro…i wanted to know if i will get only the amount of the expensive (i have X) phone or for any phone the will value the price? my cousin is coming in a few days to Chicago and i wanted to sent with her all the devices (ipones 6 *3 ,7 plus, 8 plus)